1. Field of the Invention
The present invention relates to chain-structure metal powders which are mixed with insulative materials, such as resins, rubbers, and adhesives, in order to afford electrical conductivity to such insulative materials, and to a manufacturing method of the chain-structure metal powders. In addition, the present invention relates to conductivity-afforded materials such as electrically conductive resins, electrically conductive films, electrically conductive adhesives, electrically conductive paints, and the like, which are used, for example, for electronic devices such as computers and mobile phones, and construction materials.
2. Description of the Related Art
In electronic devices, such as computers and mobile phones, and construction materials, electrical conductive resins, electrical conductive rubbers, electrical conductive films, electrical conductive adhesives, electrical conductive paints, and the like have been widely used as substitutes of solder or brazing materials for mounting or assembling electronic parts for electrostatic prevention, radio wave absorption, electromagnetic shields, etc.
In many cases, various kinds of such electrically conductive resins, rubbers, films, adhesives, paints, and the like are composites made by adding a carbon or metal powder to an insulative material such as a resin, rubber, or adhesive. For example, such composites are disclosed in Japanese Unexamined Patent Application Publication Nos. H5-81924 and 2002-60625.
However, even a carbon powder having high electrical conductivity has a high volume resistivity of approximately 1 Ω·cm; hence, it has been difficult to form an electrically conductive resin, rubber, film, adhesive, or paint which is superior in electrical conductivity.
On the other hand, a metal powder is superior in electrical conductivity, having a volume resistivity in the range of 10−6 Ω·cm. However, since particles of a metal powder are generally in the form of a sphere, oval, or scale, a large amount thereof, such as at least 20 percent by volume and preferably 30 percent by volume or more, must be added in order to afford stable conductivity to a resin, rubber, film, adhesive, and paint. As a result, in addition to economic disadvantages such as increase in cost, the addition of a metal powder has been a cause of problems such as serious side effects on the properties of an electrically conductive resin, rubber, film, adhesive, or paint. For example, the plastic deformability and/or adhesion strength of a resin may be degraded.